os.stat_float_times() was introduced in Python 2.3 to get file modification times with sub-second resolution. The default remains to get time as seconds (integer). See commit f607bdaa77475ec8c94614414dc2cecf8fd1ca0a.

The function was introduced to get a smooth transition to time as floating point number, to keep the backward compatibility with Python 2.2.

In Python 2.5, os.stat() returns time as float by default: commit fe33d0ba87f5468b50f939724b303969711f3be5.

Python 2.5 was released 11 years ago. I consider that people had enough time to migrate their code to float time :-)

I modified os.stat_float_times() to emit a DeprecationWarning in Python 3.1: commit 034d0aa2171688c40cee1a723ddcdb85bbce31e8 (bpo-14711).